【作者】 黄若双；

【导师】 林昌健； Hugh S. Isaacs；

【作者基本信息】 厦门大学 ， 物理化学， 2006， 博士

【摘要】 本文首次应用一种新的示差图像技术(Difference Viewer Imaging Technique,DVIT)研究AA7075铝合金及金属铜的局部腐蚀过程。示差图像技术的特点是能够原位、敏感地观测到用现有的其他图像技术所无法观测到的材料表面细微形貌变化。示差图像技术由于只显示样品表面特定微小区域的动态过程引起的形貌和颜色变化,可在同一时间原位提供样品表面不同位置的局部细微变化动态信息,是一种原位研究材料表面动态过程的强有力工具。(一)AA7075铝合金比强度大、导电导热性能高、耐蚀性好,在航空、汽车、建筑及电子信息等各领域有着广泛应用,但在侵蚀性环境中易发生各种形式的局部腐蚀破坏,成为当前腐蚀研究的一个重点。本研究利用示差图像技术,首次观测到机械打磨后的铝合金在氯化物溶液中发生的一种特殊形式的表面局部腐蚀——条纹腐蚀。首次提出“条纹腐蚀”的概念,系统考察了条纹腐蚀的若干关键性影响因素,对条纹腐蚀发生、发展机理进行讨论,并提出了条纹腐蚀的机理模型并进行模拟计算。主要结果如下:(1)首次观察到AA7075-T6铝合金表面经过打磨后,在NaCl溶液中表面发生的一种特殊的局部腐蚀现象,并首次提出“条纹腐蚀(Streaking Corrosion)”的概念。(2)在NaCl溶液中,AA7075-T6铝合金的条纹腐蚀主要发生在表面机械磨痕的凹槽中,腐蚀沿着磨痕方向生长,在其生长的端头附近区域为低pH的阳极区。条纹腐蚀的发展速度,包括线速度和面速度,与溶液NaCl浓度及溶液中的溶解氧含量密切相关。线速度随着氯离子浓度升高而增大,面速度在低氯离子浓度下也是随氯离子浓度升高而加速,但当NaCl浓度超过0.05 M时,因溶液中更多还原

【Abstract】 A novel technique for in situ corrosion research called Difference Viewer Imaging Technique (DVIT) was used to investigate the localized corrosion of aluminum alloys and copper for the first time in this thesis. It is an in situ, non-invasive technique displaying only the changes of morphology and color and their locations on materials surface in various environments, which is beyond the capability of the nowaday common in-situ imaging techniques. DVIT is a powerful technique for dynamic corrosion imaging, by continuously recording sequential, in situ optical images of the materials surface, and showing the differences between images through digital subtraction and multiplying the differences.AA7075 aluminum alloy has been applied in numerous fields such as aircrafts, automobiles and architectures because of its high strength and good electronic properties. However, in many environments it is susceptible to localized corrosion such as pitting and intergranular attack. The surface layer behavior of AA7075 aluminum alloy in chloride solutions is of great interest. But it is difficult to directly observe the morphology and color changes taking place on surface during open circuit immersion in chloride solutions. In this work, we observed one special kind of localized corrosion on abraded AA7075-T6 aluminum alloy surface in chloride solutions, and we named it as“Streaking Corrosion”for the first time. The corrosion behaviors of streaking corrosion and its elimination methods were systemically investigated. Here is the summary of this work:更多还原